Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) state segment	Mar. 31, 2020 USD ($)	Apr. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 19, 2018
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 58			$ 58
Expected customer life	4 years
Customer surcharges	$ 55	$ 49
Video franchise fees	$ 6	9
Funding term	7 years
Accumulated deficit	$ 8,915			$ 8,975
Operating income	259	272
Net income	$ 60	$ (186)
Number of reportable segments | segment	1
First Lien Notes due April 2027 [Member] | Secured Debt [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Interest rate	8.00%
Maturity date	Apr. 01, 2027
Second Lien Notes due 2026 [Member] | Secured Debt [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Interest rate	8.50%
Second Lien Notes Due 4/1/2026 [Member] | Secured Debt [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Interest rate					8.50%
Maturity date	Apr. 01, 2026
Subsequent Event [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Eliminated debt			$ (11,000)
CAF Phase II [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Number of states of operation | state	25